Welding equipment



May 23, 1939. H T PLATZ 2,159,860

WELDING EQUIPMENT Filed May 23, 1958 7 Sheets-Sheet l INVENTOR. Q RHenry ThomasTWatz ATTORNEYS H T. PLATZ May 23, 1939.

WELDING EQUI PMENT Filed May 25, 1938 '7 Sheets-Sheet 2 INVENiOR.

HCTHy Thomas Plalz BY W W);

ATTORNEY.5

May 23, H L TZ WELDING EQU I PMENT W MW .5

ATT

H. T. PLATZ May 23, 1939.

WELDING EQUIPMENT Filed May 23, 1938 '7 Sheets-Sheet 4 INVEN] OR.

BY p May 23, 1939. H. T. PLATZ WELDING EQUIPMENT Filed May 23, 1958 '7Sheets-Sheet 5 1N VENTOR.

m m .mo w 5A a mm 0 1 T W n e H y 23, 1939- H. T PLATZ WELDING EQUIPMENTFiled May 23, 1938 '7 Sheets-Sheet 6 INVENTOR Hen ry Thomas Platz %MJ%ATTORNEY.5

May 23, 1939. H. T. PLATZ 2,159,860

WELDING EQUIPMENT I F Fig. 12. 69 29 IN VENTOR.

ATTO

. Patented May 23, 1939 2,159,860

UNITED STATES PATENT OFFICE WELDING EQUIPMENT Henry Thomas Platz,Detroit, Mich., assignor to Briggs Manufacturing Company, Detroit,Mich., a corporation of Michigan Application May 23, 1938, Serial No.209,592

20 Claims. (01. 219-4) This invention relates generally to welding ofthe following operations in predetermined equipment and refers moreparticularly to aptimed relationship: (a) Movement of the carriageparatus for efiecting a plurality of welds autofrom one side of theapparatus to advance work matically. to be welded into registration withthe welders;

One of the principal objects of this invention is (b) Lifting the workofi the carriage into opera.- to simplify, render more eflicient andimprove tive relation to the welding devices; (c) Returngenerally theart of welding by providing welding the carriage to the loading stationfor reing apparatus which not only expediently perloading; (d) Loweringthe work on to the carriage forms the several operations required tocomplete upon completion of the welding cycle; (e) Again a welding cyclebut, in addition, performs these moving the carriage in the directionmentioned operations automatically in their proper seunder item (a) tosimultaneously move the new quence. work into registration with thewelders and the Another object of this invention resides in thecompleted work to the unloading station where provision of weldingapparatus having a reciproit is removed from the carriage.

i cable carriage movable in predetermined timed The foregoing, as wellas other objects, will relation to the operation of the welding devicesbe made more apparent as this description proto locate the work to bewelded into registration ceeds, especially when considered in connectionwith the welders and to simultaneously move the with the accompanyingdrawings, wherein: completed Work out of the apparatus. In accord-Figure 1 is a perspective view of welding ap- 20 ance with thisinvention, the work to be welded paratus constructed in accordance withthis inis positioned on the carriage at one side of the vention; vapparatus and the carriage is advanced toward Figure 2 is a sectionalplan view taken subthe opposite side of the apparatus to not onlystantiallyon the plane indicated by the line 22 position the work to bewelded into registration of Figure 1;

:3 with the welders but, in addition, to move the Figure 3 is asectional view taken substantially work previously welded to anunloading station at on the plane indicated by the line 3-3 of Figthelatter side of the apparatus. ure 2;

Still another feature of this invention consists Figure 4 is a plan viewof the welding unit; in the provision of means operating in timed Figure5 is a sectional view taken on the line I relation to movement of thecarriage to position 55 of Figure 4;

the work in registration with the welders to lift Figure 6 is asemi-diagrammatic vertical secthe work ofi the carriage into operativerelation tional view through the welding unit; to the Welding devicesand to return the carriage Figure 7 is a semi-diagrammatic elevationalto its loading station where another work piece iew, partly in section,of one of the welders;

3.) may be placed on the carriage during the inter- Figure 8 is adiagrammatic view of one of the val the work in registration with thewelding deswitches; vices is being welded. Figure 9 is a diagram of theoperation of the A further object of this invention consists inapparatus; providing mea s Op ng in timed t o to Figure 10 is asectional view taken on the line 40 completion of the welding cycle tolower the work Ill-l0 of Figure 2;

on the carriage and efi'ect the aforesaid move- Figure 11 is a sectionalview taken on the line ment of the carriage to not only introduce theil--ll of Figure 10; new work to the welding devices, but to also moveFi ur 12 1 an enlarged sectional i Showthe completed Work to e unloadingstation ing One of the welders in operative relation to r, where it isremoved from the carriage prior to the work;

return movement of the latt r to s IOading DO- Figure 13 is a detailsectional view of a portion sition. j of the machine shown in Figure 3illustrating A sti 'further advantageous feature of this the twoelectrodes in operative relation to the invention consists in theprovision of means opwork;

so erating in timed relation to lifting the work into Figure 14 is asectional view taken on the line operative relation to the welders toautomati- [4-46 of Figure 2; cally efiect one complete cycle ofoperation of Figure 15 is a sectional view taken on the line thewelders. I5|5 of Figure 2; and

In addition to the foregoing, the present inven- Figure 16 is a crosssectional view taken on the {,5 tion contemplates apparatus foreffecting each line l6l6 of Figure 3.

ill

The apparatus forming the subject matter of this invention may beconsidered as comprising generally two units, a welding unit A and. awork handling unit E. ll fhile in the illustrated em== bodiment of thisinvention both units are operated in conjunction with one another,neverth less, it is to be understood that neither unit is necessarilylimited in its use with the other. other words, the handling uru't beadvantageously employed in connection with various different types orwelding units and, of course, the welding unit illustrated may be usedwherever is desirable to ezipediently perform a series of welds. in thisconnection, it may be pointed out that the welding unit selected for thepurpose of illustrating this invention is shown and described in Zetailin my copending application Serial l lo. 210,233, filed May 26, 1938.

i-lriei-ly described, the welding rnlt comprises two oi welders C and D,each. bank having a plurality of groups of welders E provided withelectrodes F movable toward and. away from the work. The groups E ofwelders in each bank are successively operated in a manner such that theelectrodes F or the welders in each group are simultaneously moved byfluid pressure into clamping engagement with the work and are returnedto their inoperative positions by means the springs G acting on theundersides of the electrode operating pistons iii in the manner clearlyshown in Figure 7 or the drawings.

the specific embodiment of the invention selected for the purpose ofillustration, the appa= ratus is designed to weld. the marginal edges ofn inner vehicle door panel D to the marginal edges of the outer panel Dof the door. In Figure 13 or the electrodes F are shown as engaging thetree marginal edge of the return-bent flange on the outer door panel andthe cooperating electrode F is ihustrated as abutting the inner doorpanel adjacent the marginal edge of the latter which extends into thereturn-bent flange on the outer door panel. The electrode F iselectrically connected to -a bus bar which in turn is connected in thewelding circuit with the electrodes F, according to orthodox practice,with the result that current flows through the return-bent flange of theouter door panel to the interfitting marginal flange or" the inner doorpanel and, in this manner, integrally connects the same together.

Upon reference to Figure 6, it will be noted that hydraulic fluid mediumunder pressure is successively supplied to the groups E of welders inboth banks by a distributing valve I having an arm J provided with afluid passage therethrough and secured at the inner end to the upper endof a vertically extending hollow shaft K with the passage through thearmcommunicating with the passage through the shaft. The shaft K isjournalled in a reservoir L containing the hydraulic fluid medium and isdriven by an electric motor M through suitable reduction gearing l. Apump 0 is supported in the reservoir below the level of the hydraulicfluid medium and is adapted to supply fluid under pressure to thecommunicating passages in the shaft K and. arm J. A nozzle P is securedto the radially outer end of the arm in communication with the passagetherethrough and successively registers with circumferentially spacedports Q formed in the undersidebf the distributing plate B.

Each of the ports Qin the plate It communicates with the inner end of aradially outwardly extending passage Sin the plate R, and the outerarc-aged end of each passage S communicates with the cylinders of. thewelders of one group E at a point above the electrode operating pistonsH through the medium of flexible conduits.

From the foregoing, it will be noted that fluid pressure successivelysupplied to each of the passages S by the nozzle P is discharged fromeach passage S into the pressure cylinders of the associated group ofwelders at points above the electrocle operating pistons H in thepressure cyllnders. As a result, the pistons H are moved against theaction of the springs in a down ward. direction to effect movement ofthe electrodes F into clamping engagement with the stock to be welded.l'hus, it will be seen that the electrodes or the welders in each groupE are simultaneously moved into engagement with the work as the groupsof welders in both banks are successively connected to the nozzle P ofthe distributing valve 1. The fluid under pressure is continuouslysupplied to each group of welders until the nozzle P is moved by the armJ out of registration with the associated port At this time, the port isopened to the interior or" the reservoir L and the pressure on the inthe associated group of welders immediately drops to such an extent asto permit the electrodes F to be moved away from the work by the springsFor the purpose of illustration, all of the the welders in the group Care arranged in an electric circuit controlled by the switch rill andall of the welders in the group D are arranged in another electriccircuit controlled by a switch ll. Both of the switches are identical inconstruction and operate automatically by fluid pressure to close andopen their respective circuits in timed relation to movement of theelectrodes into and out of engagement with the work. Although the twoswitches are identical in construction, nevertheless, they may beindependently adjusted so that the welding time of the welders in thebank C may either be the same 01 different from the welding time of thewelders in the bank D. For example, in cases where both welders operateon stock having the same characteristics and thicknesses, both switchesmay be operated in unison so that the welding time of all of the weldersin both banks is the same. However, if the welders in the bank D areadapted to operate on stock having a thickness less than the stock uponwhich the welders in the bank C operate, the switch 2| is adjusted sothat the welders in the bank D have a shorter welding time than thewelders in the bank C. In either case, however, the switches operate toclose their respective circuits after the electrodes are moved intoengagement with the work and to open the circuits before the electrodesare retracted from the work.

As stated above, the switches are automatically operated by fluid underpressure in timed relation to movement of the electrodes F into and outof engagement with the work. In the present instance, each switch isoperated by air under pressure and, in general, the flow of air to theswitch 20 is controlled by a plurality of valves 22, while the flow ofair under pressure to the switch M is controlled by a similar series ofValves 23. The number of valves 22 corresponds to the number of groups Eof welders in the bank C, and the number of valves 23 corresponds to thenumber of groups E of welders in the bank D. The Valves are successivelyoperated by the distributing valve I to open communication between thesource of air under pressure and the interior of the switches at thesame time that 15 the electrodes of the groups oi welders are moved ofcourse, follows from the above that when one group of welders in thebank D is relatively moved into engagement with the stock by thehydraulic fluid under pressure supplied to the distributing valve I, theair valve 23 associated with this group of welders is automaticallyopened to determine the passage of air into the switch 2| controllingthe welding circuit to the groups of welders in the Bank D.

It will also be understood that independent air supply lines 24 and 2|are provided for the switches "and 2|, respectively. The air supply line24 is adapted to communicate with the switch through an air distributingline 20 when any one of the valves 22 is opened and the air supply line25 communicates with the switch 2| through the air distributing line 21when any one of the valves 23 is opened.

Each of the valves is urged to its closed position by means of a spring28 and the valves are successively moved to their open positions againstthe action of the springs by means of the hydraulic fluid under pressuresupplied to the welders by the distributingvalve I. For accomplishingthis result, each valve is provided with a follower 29 slidably mountedin a bushing 30 and having a head 3| seated on the upper end of thebushing directly beneath the stem 22 of each valve. The bushings ill arethreaded in the top surface of the distributing plate R in a position sodetermined that one bushing communicates with each fluid pressurepassage 8 in the'plate R. As a result, the lower ends of the followersare exposed to the hydraulic fluid under pressure in the passages S, andthese followers are moved upwardly by the fluid pressure in the latterpassages to, in turn, ei!ect an upward movement of the valves.

Fluid pressure operated switches 20 and 21 Although the admission of airunder pressure to the switches 20 and 2| is controlled by thedistributing valve I in a manner that the air is admitted to one or theother of the switches at the same time the electrodes of one group E ofwelders are moved into engagement with the work by thedistributing-valve I, nevertheless, the actual operation of the switchesto close and open the circuit to the group of welders being operated bythe distributing valve I is controlled independently of the movement ofthe electrodes into engagement with the work. with this arrangement, theduration of the welds may be accurately varied within definite limits wthough the time interval that the electrodes of the several groups ofwelders are maintained into engagement with the work is uniform.

Inasmuch as the construction and operation of both switches areidentical, a description of the switch 20 will sufllce for bothswitches. The switch 20 is diagrammatically shown in Figure 8 of thedrawings, and it is believed that the operation of this switch will bereadily understood upon considering this flg'ure in conn ction with thefollowing description. When any one of the valves 22 associated with thebank C of welders is opened, air under pressure flows from the supplyline 24 to the distributing line 20 and is discharged into the switch 20through a port SI.

The air under pressure flowing through the port II is discharged into ae 38 having one end communicating with the switch chamber 81 through themedium of a restricted port it and having the opposite end communicatingwith an accumulating chamber II through the medium of a metering valve40. The air under pressure in the switch chamber 81 acts upon theplunger H in the chamber and, when this air pressure exceeds the forceexertedby the spring 42, the plunger 4| is moved against the action ofthis spring in a direction toward the stationary contact member 43 toengage thecontacts on the plunger ll with the contacts I! on the fixedmember 43. It will, of course, be understood that the contacts areinsulated from one another and that the cooperating contacts of eachpair are the work.

The air under pressure also builds up in the accumulating chamber 38 ata rate determined by the adjustment of the needle valve ill, and thisair under pressure is discharged into the switch chamber 31 between themovable and stationary contact carrying members I and 43 through themedium of a passage 41. when the pressure of the air between the contactcarrying members approximates the air pressure acting on the oppositeside of the movable contact member 4|, the latter is moved to its freeposition by the spring 42, with the result that the circuit to theelectrodes is opened. It follows from the above that the time intervalof opening of the switch or the duration of the weld may be accuratelycontrolled by adjusting the needle valve ll. In any case,

however, the needle valve is so adJusted that the switch 20 will openthe welding circuit before the electrodes are. moved out of engagementwith the work.

Inasmuch as the switch 20 is employed to control all of the welders inthe bank C, therate of operation of the several groups of welders inthis bank depends to some extent upon the rapidity with which the switch20 can be operated. For this reason, provision is made herein forquickly exhausting the air under pressure from the accumulating chamberand switch chamber 31 after each operation of the switch.

Referring again to Figure 8 of the drawings,

it will be noted that exhausting the switch 20 is eflected by an exhaustvalve 48 housed in the interior of the bore and the atmosphere. Theinterior of the bore 50 also communicates at points spacedcircumferentially from the exhaust port 52 with the accumulating chamber39 and the switch chamber 31.. As shown in Figure 8, the accumulatingchamber 39 communicates with the interior of the bore through the mediumof a passage 53 and the switch chamber 3'! communicates with theinterior of the bore 50 through the medium of a passage 54. Thedischarge ends of the passages 53 and 54 communicate with the bore 50 insuch a manner that when the plunger 49-is in its normal position shownin Figure 8, these passages, as well as the exhaust port 52, are closedby the valve plunger.

It follows from the above that the valve plunger 49 must be moved in adirection away from the plug 5| in order to establish communicationbetween the exhaust port 52 and the passages 53 and 54. Movement of theexhaust valve plunger 49 in the above mentioned direction is resisted bymeans of the air pressure from the distributing line 26 whichcommunicates with the bore 50 through the medium of a passage 55. Theair under pressure supplied to the bore 5!) acts upon one of a pin 56slidably mounted axially of the bore 50 in a bushing 5'! and having theopposite end abutting the valve plunger 43. The pressure of the airdischarged into the bore 50 through the passage is greater than theforce of the spring 58 acting upon the valve plunger 49 tending to movethe same against the action of the air under pressure.

It follows from the above that the air from the distributing line 26maintains the exhaust valve closed against the action of the spring 58until the force exerted by the latter is supplemented with an additionalforce sufiicient to overcome the pressure of the air on the pin 55. Asshown in Figure 8, this additional force is supplied by air pressurebuilt up in a second accumulating chamber by means of a passage 6! andcommunicates with the bore 50 by means of a passage 62. The passage 652communicates with the bore 50 at a point beyond the end of the plunger59 acted upon by the spring 58 and, in

the present instance, the plug 5i is formed with a series of passages 53therethrough to provide for the flow of air against the side of theplunger 49 acted upon by the spring 58. As a result of the above, theair pressure supplied to the bore 55 from the accumulating chamber 55supplements the action of the spring 58 to move the valve plunger 49against the action of the fluid pres sure acting en the pin 55 and toopen communication between the exhaust port 52 and the passages 53 and54. It may be pointed out at this time that the diameter of the pin 55is substantially less than the diameter of the valve plunger 49, withthe result that the area exposed to the air pressure entering the bore55 from the passage 55, tending to hold the valve plunger in a positionwherein the exhaust port 52 is closed, is less than the area of thevalve plunger exposed to the action of the fluid pressure admitted tothe bore 50 from the accumulating chamber 50.

As soon as the valve plunger 49 is moved away from the plug 56 by thecombined effort of the spring 58 and the air pressure supplied by theaccumulating chamber 60, the exhaust port 52 is connected to thepassages 53 and 54 with the result that the switch is immediatelyexhausted to the atmosphere. The time interval of operation of theexhaust valve to exhaust the switch depends upon the rate at whichpressure builds up in the accumulating chamber 60 and this rate iscontrolled by a metering valve similar to the metering valve 40 andlocated in the passage 6| between the accumulating chamber 39 and theaccumulating chamber 60. The metering valve 65 is accurately adjusted todelay operation of the exhaust valve until the welding circuit has beenopened by movement of the switch plunger 4| in a direction away from thefixe contact carrying member 43.

Work handling unit B The work handling unit B comprises a rectangularcarriage 65 mounted for reciprocation in a horizontal plane beneath thewelding unit A between a loading station 61 and an unloading station 68.The carriage 66 is slidably mounted on a track 69 supported from thebase 10 of the machine by means of diagonal braces H having the innerends fixedly secured to the base 10 and having the outer ends secured tothe track. Upon reference to Figure 2, it will be noted that a pluralityof rollers 12 are secured to each side bar '13 of the carriage in spacedrelation to each other longitudinally of the side bars and adapted toengage the too surfaces of the side bars 14 of the track 69. The Widthof the carriage 66 and the depth of ti": side bars I3 thereof arepredetermined to rovide for frictional engagement of the outer sidesurfaces of the bars 13 adjacent the bottom longitudinal edges thereofwith the inner surfaces of the side bars 14 of the track 69. As aresult, lateral displacement of the carriage 66 relative to the track isprevented.

Mounted on the carriage for movement as a unit therewith is a pair ofwork supports, designated generally in the several figures by thereference characters 15 and 16. The work support l5 comprises a pair ofmembers 11 respectively secured to the opposite side bars 13 of thecarriage and having top surfaces I8 extending above the side bars of thecarriage to form a rest upon which the work is positioned. Each of themembers ill is formed with upwardly extending flanges it? at oppositeends providing shoulders engageable with opposite sides of the work formoving the work as a unit with the carriage.

When the carriage is in the extreme position shown in Figures 1 and 2,the work support 15 is located at the loading station 61 and the work tobe welded is placed on the work support 15. As stated above, the machineforming the subject matter of this invention is designed to weld theinner and outer panels of a vehicle body door together. The outline ofthe door is designated in Figure 2 by the reference character 81 andthis door is positioned on the work support 15 transversely of thecarriage between the shoulders 80 on the work supporting members 11. Thedoor 8i is positioned laterally with respect o the carriage by means ofthe guide plates 82 fixedly secured to the track 69 at opposite sides ofthe carriage. The guide plates 82 are pr determinedly located withrespect to the welders so that the proper portions of the door willregister with the electrodes F of the welders when the door ispositioned in operative relation to the electrodes.

After the door 8| to be welded has been properly positioned on thecarriage 66, the latter is moved to the position shown in Figure 3wherein the door is in registration with the electrodes F of the Weldersin the welding unit. The door is then lifted oh the work support 15 andmoved into operative relationship with the electrodes F of the welders,as shown in Figure 1. This is accomplished by a vertically movableplaten 83 supported below the carriage 66 directly beneath the weldersfor reciprocation toward and away from the welding unit A. Uponreference to Figure 3, it will be noted that the platen 83 isreciprocated by an air cylinder 84 secured to the base I of the machinesubstantially centrally of the latter and having a piston 85 operativelyconnected to the center of the platen 83 by means of a connecting rod86. The platen is guided throughout reciprocation thereof by verticalstanchions 81 and bearings 88 secured to the platen in positions torespectively slidably engage the stanchions 81. The lower ends of thestanchions 81 are fixed to the base I0 and the upper ends thereof aresecured to the welding unit A for supporting the latter from the base.

Mounted upon the top surfaceof the platen is a sectional work raisingmember 89 having the sections thereof predeterminedly spaced from eachother to provide for extending the member upwardly between the side barsof the track and carriage. Also, the arrangement and contour of thesections of the member 89 are determined to provide an outlineconforming to the outline of the door 8|. In this connection, it may bepointed out that the welders associated with the welding unit A arepredeterminedly located so that the electrodes F of the welders arearranged on an outline which also corresponds to the outline of the door8|. As a result, upward movement of the member 89 by the platen 83 liftsthe door 8| off the carriage 66 into operative relationship to theelectrodes F of the welders and movement of the electrodes F to theiroperative positions serves to clamp the marginal edge portions of thedoor 8| between the member 89 and the electrodes F. As shown in Figure13, the electrodes F on the welders E engage the marginal return-bentflange on the outer panel D when the door 8| has assumed its uppermostposition. It will also be observed from Figure 13 that movement of thedoor 8| to its upper position by the platen 83 causes the cooperatingfixed electrodes F to engage the inner panel D, with the result that acircuit is established through the two panels to the electrodes.

The door 8| is centered on the lifting member or electrode 89 by meansof the spaced projections 90 extending upwardly from the varioussections of the member 89 and is initially yieldably'clamped against themember 89 by means of the clamps 9| shown in Figure 12 as supported onthe welding unit A for engagement with the upper surface of the door.The clamps 9| are normally yieldably urged in a direction toward thedoor by means of the springs 92 which are tensioned when the member 89is moved to its uppermost position by the platen 83. As will be morefully hereinafter set forth, the welding unit A is operated in timedrelation to upward movement of the door 8| to supply an electric currentfrom one electrode F to the cooperating electrode F through the innerand outer panels of the door to integrally secure the same together.

The carriage 66 is returned to its initial starting position shown inFigure 2 as soon as the door BI is lifted from the work support I by theplaten 83. When the carriage is in the above mentioned position shown inFigure 2, the work support I5 assumes a position directly beneath thedoor 8| which is being welded by the welding unit. The work support I6also comprises a pair of members 93 respectively secured to oppositesides of the carriage 66 and having a top surface 94 upon which the workis adapted to be supported when the member 89 is lowered from itsoperative position shown in Figure 3. The ends of the members 93adjacent the work support 15 are provided with upwardly extendingflanges 95 forming shoulders 96 adapted to engage the adjacent side edgeof the completed door 8| and to move the door to the unloading station68 when the carriage 66 is again actuated to position the work supportI5 in registration with the welding unit A.

Located at the unloading station 68 is a work support 91 comprisinglaterally spaced bars 98 secured in any appropriate manner to theadjacent portions of the track 69. A series of rollers 99 are rotatablymounted on each bar 98 in spaced relationship longitudinally of thebars. The elevation of the rollers relative to the elevation at whichthe completed door 8| is supported by the carriage is predetermined sothat when the work support I6 assumes a position at the unloadingstation 68, the door 8| rides up on the rollers 99. As a result, whenthe carriage is again returned to its initial starting position shown inFigure 2, the door is left on the rollers and may be removed during thenext cycle of operation. Of course, it will be understood that thecarriage is not returned to its initial starting position until the newdoor to' be welded has been lifted off the carriage by the platen 83. Itmay also be pointed out at this time that the carriage is cushioned ateach end of its travel by a pair of dashpots I00 respectively secured toopposite ends of the track and having plungers IOI engageable with themounting brackets I02 for the rollers I2 on the carriage.

The carriage is reciprocated by an air cylinder I03 fixedly supported inany suitable manner on the machine frame and having a piston I04reciprocably mounted therein. This construction is shown in Figure and,as will be noted from this figure, the piston is secured to the carriageby means of the rod I05. Fluid under pressure is alternately admitted toand exhausted from the cylinder I03 at opposite ends of the piston bymeans of fluid pressure supply lines I06 and I01, respectively. The rateof flow of fiuid under pressure through each of these supply lines tothe cylinder is controlled by a needle valve I09 with the result thatthe rate of movement of the carriage may be varied.

Operation The operation of the various instrumentalities of the handlingunit B and the operation of the welding unit are effected automaticallyin predetermined timed relationship upon closing the main switch IIO bythe operator. The control button III for closing the switch H0 isconveniently mounted at the loading station 81 for manipulation by theoperator. Manipulation of the push button II I by the operator closes acircuit to the relay H2 and the latter, in turn, closes a circuit to thecoil II3 of an electromagnet II I having a movable armature II5.Movement of the armature I I5 into the magnetic field of the coil 3operates the valve M6 to open communication between the fluid pressuresupply line II! and cylinder I03 to the passage I06. In addition,operation of the valve I I6 by the armature H5 establishes communicationbetween the opposite end of the air cylinder I03 and the at-.

mosphere through the passage I01 to exhaust the fluid pressure on theopposite side of the piston I04. As a result, the piston I04 is moved inthe direction of the arrow H8 and the carriage 66 is moved in acorresponding direction to locate the work support 15 in registrationwith the welding unit A. It may be pointed out in this connection that alimit switch .9 is arranged in series in the circuit with the switch II0 and this switch is normally maintained closed in the lower positionof the platen by the projection I20 fixed to the platen. The arrangementis such that when the platen is in any one of its raised positions, thelimit switch H9 is open and the switch I I0 is rendered inoperative toafiect the circuit. Of course, opening of the switch II9 by upwardmovement of the platen does not deenergize the electromagnet I4 becausethe relay II2 is latched in its closed position by means of the latchI2I.

As the carriage 66 is moved in the direction of the arrow II8, the limitswitch I22, mounted on the track 69, is actuated by the carriage toclose a circuit to the relay I23 and the latter is immediately latchedin its closed position by means of the latch I24. The relay, in turn,closes a circuit to the coil I25 of the electromagnet I26 and movementof the armature I21 into the magnetic field efiects operation of thevalve I28 to establish communication between the fluid pressure supplyline II 1 and the lower end of the cylinder 84. Operation of the valve I28 by the electromagnet I26 also closes the exhaust for the cylinder 84so that the piston 85 in the cylinder is moved upwardly by the air underpressure. Upward movement of the piston 85 effects a correspondingupward movement of the platen 83 to lift the door assembly 8I from thecarriage 66 into operative position with the electrodes F and F of thewelders in the welding unit A. As the platen 83 is moved upwardly tolift the door from the carriage, the limit switch I29 on one of thestanchions 81 of the machine is operated by the projection I30 on theplaten to close a circuit to the electromagnet I 3| associated with thelatch I2I of the relay II2. Energization of the coil I32 of theelectromagnet I3l sets up a field suflicient to attract the latch memberI2I and move the latter in a direction to permit the relay II2 to open.In this connection, it will, of course, be noted that initial upwardmovement of the platen 83 opens the limit switch II9 so that the switchH9 is rendered inoperative. It will, of course, be understood that thecoil I33 of the relay is de-energized as soon as the operator releaseshis hand from the push button III. As a consequence, as soon as thelatch I 2| is operated to release the relay, the circuit to theelectromagnet H4 is opened and the valve H6 is actuated by the springII4 permitting the fluid under pressure in the cylinder I03 to exhaustthrough the passage I06 and permitting fluid under pressure from thesupply line II1 to enter the opposite end of the cylinder through thepassage I01. The arrangement is such that the piston I04 in the cylinderI03 is moved in the direction of the arrow I35 to effect a returnmovement of the carriage 66 to its original starting position. As theplaten 83 continues its upward movement, the limit switch I36 isactuated by the projection I30 on the platen to close a circuit to themotor M. It will be remembered that the motor M operates thedistributing valve I of the welding unit and effects one complete cycleof operation of the welding unit in the manner clearly defined above.The motor M also operates a contact disc I31 and this contact disccarries a projection I38 predeterminedly arranged to operate a limitswitch I39 to open the circuit to the motor M upon completion of thewelding operation.

In addition, the contact disc I31 is provided with another projectionI40 predeterminedly located to actuate the limit switch I4I to close acircuit to the electromagnet I42 associated with the latch I24.Energization of the coil I43 of the electromagnet I42 attracts the latchI24 and moves the same to its released position. As a result; theelectromagnet I26 is de-energized and the valve I 28 is operated by thespring I44 to establish communication between the lower end of thecylinder 84 and exhaust. This allows the platen 83 and member 89 to movedownwardly to its initial starting position. During the downwardmovement of the platen, the completed work is positioned on the worksupport 16 on the carriage in readiness for movement by the carriage tothe unloading station when the push button III is again manipulated bythe operator to insert another door to be Welded into the machine. Inorder to insure maintaining the platen 83 in its uppermost positionuntil the carriage has been moved to locate the work support 16 directlybeneath the work, a limit switch I50 may be located in series with theswitch MI and secured to the track 69 in a position to be closed by thework support 16 when the latter has assumed a position directly beneaththe completed work.

What I claim as my invention is:

1. In welding apparatus, a plurality of welders having electrodesmovable into and out of clamping engagement with the work and arrangedin an electric circuit, a work supporting carriage movable from aloading station to a position wherein the work is in registration withthe electrodes of the welders, means operated by the carriage in timedrelation to movement of the carriage to position the work inregistration with the electrodes to move the work off the carriage intooperative relation to the electrodes, means operating in timed relationto the last named means to move the electrodes into and out of clampingengagement with the work, and means for closing and opening the circuitin timed relation to movement of the electrodes into and out of clampingengagement with the work.

2. In welding apparatus, a plurality of Welders having electrodesmovable into and out of clamping engagement with the work and arrangedin an electric circuit, a work supporting carriage movable from aloading station to a position wherein the work is in registration withthe electrodes of the welders, means operating in timed relation tomovement of the carriage to position the work in registration with theelectrodes to move the work off the carriage into operative relation tothe electrodes, means operated by the last named means in-timed relationto movement of the work into operative relation to the electrodes toeffect movement of the electrodes into and out of clamping engagementwith the work, and means responsive to operation of the electrode movingmeans to close and open the circuit to the electrodes in timed relationto movement of the electrodes into and out of clamping engagement withthe work.

3. In welding apparatus, a plurality of welders having electrodesmovable into and out of clamping engagement with the work and arrangedin an electric circuit, a work supporting carriage movable from aloading station to a position wherein the work is in registration withthe electrodes oi the welders, means operated by the e in timed relationto movement of the latter to position the work in registration with theelectrodes to lift the work the carriage to a position in operativerelation to the electrodes, and means operated by' said lifting means tomove the electrodes into and out of clamping enmovable, from a loadingstation to a position wherein the work is in registration with theelectrodes oi the welders. means operating in timed relation to movementof the carriage to position the work in registration with the electrodesto move the work oil the carriage into operative relation to theelectrodes, means operating in timed relation to movement of the workoil the carriage to return the carriage to its loading station, andmeans operating in timed relation to movement or the work into operativerelation to the welders to move the electrodes into and out of clampingengagement with the work and to close an open the electric circuit tothe electrodes in timed relation to movement or the latter into and outoi! clamping engagement with the work.

5. In welding apparatus, a plurality of welders having electrodesmovable into and out of clamping engagement with the work and arrangedin an electric circuit, a work supporting carriage movable from aloading station to a position wherein the work is in registration withthe electrodes oi the welders, means operated by the carriage in timedrelation to movement of the latter to position the work in registrationwith the electrodes to lift the work oil the carriage to a position inoperative relation to the electrodes. means operated by the liftingmeans to return the carriage to its leading station, and means alsooperated by the lilting means in timed relation to movement of the workinto operative relation to the electrodes to move the electrodes intoand out of clamping engagement with the work and to close and open theelectric circuit to the electrodes in timed relation to movement oi thelatter into and out of clamping engagement with the work.

6. .In welding apparatus, a plurality of welders having electrodesarranged in an electric circuit, a work supporgng carriage movable froma loading station to a position-wherein the work is in registration withthe electrodes 01 the welders, means operating in timed relation tomovement of the carriage to position the work in registration with theelectrodes to move the work of! the carriage into operative relation tothe electrodes, means operating in timed relation to the last namedmeans to close and open the electric circuit to the electrodes, andmeans operating in timed relation to opening of the electric circuit tothe electrodes to return the work in supporting relation to thecarriage.

7. In welding apparatus, a plurality of welders having electrodesmovable into and out or clamping engagement with the work'and arrangedin an electric circuit, a work supporting carriage movable from aloading station to a position wherein the work is in registration withthe electrodes of the welders, means operating in timed relation tomovement of the carriage to position the work in registration with theelectrodes to move the work oi! the carriage into operative relation tothe electrodes, means operating in timed relation to movement 01 thework of! the carriage to return the carriage to its loading station,means operating in timed relation to movement of the work into operativerelation to the welders to move the electrodes into and out of clampingengagement with the work and to close and open-the electric circuit tothe electrodes in timed relation to movement of the latter into and outof clamping engagement with the work, and means operating in timedrelation to movement of the electrodes out of clamping engagement withthe work to return the work in supporting relation to the carriage.

8. In welding apparatus. a plurality of welders having electrodesmovable into and out of clamping engagement with the work and arrangedin an electric circuit, a work supporting carriage movable from aloading station to a position wherein the work is in registration withthe electrodes of the welders, means operated by the carriage in timedrelation to movement of the latter to position the work in registrationwith the electrodes to lift the work off the carriage to a position inoperative relation to the electrodes, means operated by said liit'ngmeans to move the electrodes into and out of clamping engagement withthe work and to close and open the electric circuit to the electrodes intimed relation to movement of the latter into and out of clampingengagement with'the work, and means operating in timed relation tomovement of the electrodes out of clamping engagement with the work toreturn the work to a position on the carriage.

9. In welding apparatus, a. plurality of welders having electrodesmovable into and out of clamping engagement with the work and arrangedin an electric circuit, a work supporting carriage movable from aloading station to a position wherein the work is in registration withthe electrodes of the welders, means operated by the carriage in timedrelation to movement of the latter to position the work in registrationwith the electrodes to lift the work of! the carriage to a position inoperative relation to the electrodes, means operated by the liftingmeans to return the carriage to its loading station, means also operatedby the lifting means in timed relation to'movement oi the work intooperative relation to the electrodes to move the electrodes into and outof clamping engagement with the work and to close and open the electriccircuit to the electrodes in timed relation to movement of the latterinto and out of clamping engagement with the work, means operating intimed relation to movement of the electrodes out of clamping engagementwith the work to return the work to a position on the carriage, and anunloading station upon which the completed work is deposited uponmovement of the carriage to register the work located thereon at theloading station with the electrodes of the welders.

10. In welding apparatus, a plurality of welders having electrodesmovable into and out of clamping engagement with the work and arrangedin an electric circuit, a work supporting carriage movable from aloading station to a position wherein the work is in registration withthe electrodes of the welders, means operating in timed relation tomovement of the carriage to position the work in registration with theelectrodes to move the work off the carriage into operative relation tothe electrodes, means operating in timed relation to movement of thework off the carriage to return the carriage to its loading station,means operating in timed relation to movement of the work into operativerelation to the welders to move the lectrodes into and out of clampingengagement with the work and to close and open the electric circuit tothe electrodes in timed relation to movement of the latter into and outof clamping engagement with the work, means operating in timed relationto movement of the electrodes out of clamping engagement with the workto return the work in supporting relation to the carriage, and meansresponsive to movement of the carriage to register additional work withthe electrodes of the welders to remove the completed work from thecarriage.

11. In Welding apparatus, a plurality of welders having electrodesmovable into and out of clamping engagement with the work and arrangedin an electric circuit, a reciprocable carriage having spaced worksupporting portions, means for reciprocating the carriage to alternatelymove one of the portions between a loading station and a position inregistration with the electrodes of the welders and to alternately movethe other portion between an unloading station and a position inregistration with the Welders, means operating in timed relation tomovement of the carriage in a direction to move the first worksupporting portion from the loading station to a position inregistration with the electrodes to lift the work from the carriage intooperative relation with the electrodes, means operating in timedrelation to the operation of the lifting means to move the electrodesinto and out of clamping engagement with the work and to close and openthe electric circuit to the electrodes in timed relation of movement ofthe latter into and out of clamping engagement with the work, means alsooperating in timed relation to the operation of the lifting means formoving the carriage in the opposite direction to return said first worksupporting portion to the loading station, and means operating in timedrelation to movement of the electrodes out of clamping engagement withthe work to lower the work on the second named work supporting portionfor movement by the latter to the unloading station upon movement of thecarriage in the first mentioned direction to locate the new work inregis= tration with the welders.

12. In welding apparatus, a plurality of weld ers having electrodesmovable into and out of clamping engagement with the work and ar-=ranged in an electric circuit, a reciprocable car riage having spacedwork supporting portions, means for reciprocating the carriage to alternately move one of the portions between a loading station and a positionin registration with the electrodes of the welders and to alternately,

move the other portion between an unloading station and a position inregistration with the welders, means operating in timed relation tomovement of the carriage in a direction to move the first worksupporting portion from the loading station to a position inregistration with.

ment with the work, means also operated by the lifting means in timedrelation to operation of the latter to lift the work from the carriageto move the latter in the opposite direction to return the first name-dwork supporting portion to the loading station, means operating in timedrelation to movement of the electrodes out of clamping engagement withthe work to lower the work on the second named work supporting portionfor movemtnt by the latter to the unloading station upon movement of thecarriage in the first mentioned direction to locate the new work inregistration with the welders, and means for removing the completed workfrom the second named portion of the carriage prior to return movementof the latter to locate the first portion at the loading station.

13. In welding apparatus, a plurality of welders having electrodesarranged in an electric circuit, work supporting means movable from aloading station to a position wherein the work is in registration withthe electrodes of the welders, means operating in timed relation tomovement of the work supporting means to position the work inregistration with the electrodes to move the work off the worksupporting means into operative relation to the electrodes, and meansoperated by the lifting means in timed relation to movement of the workoil the supporting means into operative relation to the electrodes forclosing and opening the circuit to the electrodes.

14. In welding apparatus, a' plurality of welders having electrodesarranged in an electric circuit, work supporting means movable from aloading station to a position wherein the work is in registration withthe electrodes of the welders, means operated by the work supportingmeans in timed relation to movement of the latter to position the workin registration with the electrodes to lift the work off the supportingmeans in operative relation to the electrodes, and means operated by thelifting means to close and open the electric circuit to the electrodesin timed relation to movement of the work into operative relation tosaid electrodes.

15. In welding apparatus, a plurality of welders having electrodesarranged in an electric circuit, work supporting means movable from aloading station to a position wherein the work is in registration withthe electrodes of the welders, means operated by the work supportingmeans in timed relation to movement of the latter to position the workin registration with the electrodes to lift the work off the supportingmeans in operative relation to the electrodes, means operated by thelifting means to return the supporting means to said loading position,and means also operated by the lifting means to close and open theelectric circuit to the electrodes in timed relation to movement of thework into operative relation to said electrodes.

16. In welding apparatus, a plurality of welders having electrodesarranged in an electric circuit, work supporting means movable from aloading station to a position wherein the work is in registration withthe electrodes of the welders, means operating in timed relation tomovement of the work supporting means to position the work inregistration with the electrodes to move the work oh. the worksupporting means into operative relation to the electrodes, meansoperating in timed relation to movement of the work off the supportingmeans to return the supporting means to its loading position, and meansfor closing and opening the circuit to the electrodes in timed relationto movement of the work 011 the supporting means into operativerelationv to the electrodes.

17. In welding apparatus, a plurality of welders having electrodesarranged in an electric circuit, work supporting means movable from aloading station to aposition wherein the work is in registration withthe electrodes of the welders, means operating in timed relation tomovement of the work supporting means to position the work inregistration with the electrodes to move the work off the worksupporting means into operative relation to the electrodes, meansoperating in timed relation to movement 01 the work off the supportingmeans to return the supporting means to its loading position, means forclosing and opening the circuit to the electrodes in timed relation tomovement of the work off the supporting means into operative relation tothe electrodes, means operating in timed relation to opening of thecircuit to the electrodes to return the work to the supporting means,and means responsive to movement of the supporting means to registeradditional work thereon with the electrodes to remove the completed workfrom the supporting means.

18. In welding apparatus, a plurality of welders having electrodesarranged in an electric circuit, work supporting means movable from aloading station to a position wherein the work is in registration withthe electrodes of the welders, means operating in timed relation tomovement of the work supporting means to position the work inregistration with the electrodes to move the work off the worksupporting means into operative relation to the electrodes, meansoperating in timed relation to movement of the work of! the supportingmeans to return the supporting means to its leading position, means forclosing and opening the circuit to the electrodes in timed relation tomovement of the work oil? the supporting means into operative relationto the electrodes, means operating in timed relation to opening of thecircuit to the electrodes to return the work to the supporting means,and an unloading station located to receive the completed work uponmovement of the supporting means to position additional work thereon inregistration with the electrodes.

19, In welding apparatus, a plurality of welders having electrodesarranged in an electric circuit, a reciprocable carriage having spacedwork supporting portions, means for reciprocating the carriage toalternately move one of the portions between a loading station and aposition in registration with the electrodes of the welders and toalternately move the other portion between an unloading station and aposition in registration with welders, means operating in timed relationto movement of the carriage in a direction to move the first worksupporting portion from the loading station to a position inregistration with the electrodes to lift the work from the carriage intooperative relation with the electrodes, means operating in timedrelation to the operation of the lifting means to close and open theelectric circuit to the electrodes, means also operating in timedrelation to the operation of the lifting means for moving the carriagein the opposite direction to return said first work supporting portionto the loading station, and means operating in timed'relation to openingof the circuit to the electrodes to lower the work on the second namedload supporting portion for movement by the latter to the unloadingstation upon movement of the carriage in the first mentioned directionto locate the new work in registration with the welders.

20. In welding apparatus, a plurality of welders having electrodesarranged in an electric circuit, a reciprocable carriage having spacedwork supporting portions, means for reciprocating the carriage toalternately move one of the portions between a loading station and aposition in registration with'the electrodes of the welders and toalternately move the other portion between an unloading station and aposition in registration with welders, means operated by the carriage intimed relation to movement of the carriage in a direction to move thefirst work supporting portion from the loading station to a position inregistration with the electrodes to lift the work from the carriage intooperative relation with the electrodes, means operated by the liftingmeans in timed relation to movement of the latter to locate the work inoperative relation to the welders to close and open the electric circuitto the electrodes, means also operated by the lifting means in timedrelation to operation of the latter to lift the work from the carriageto move the latter in the opposite direction to return the first namedwork supporting portion to the loading station, means operating in timedrelation to opening of the circuit to the electrodes to lower the workon the second named load supporting portion for movement by the latterto the unloading station upon movement of the carriage in the firstmentioned direction to locate the new work in registration with thewelders, and means for removing the completed work from the second namedportion of the carriage prior to return movement of the latter to locatethe first 6 portion at the loading station.

HENRY THOMAS PLATZ.

